Electric cartridge type heater

ABSTRACT

The electric cartridge type heater has a continuous central fitting hole ( 2 ) for receiving a cylindrical body to be healed in a gap-free manner, an inner metal jacket ( 1 ), an outer metal jacket ( 3 ) and a healing conductor wound on the circumference of a coil form ( 8 ), which is inserted in an annular chamber ( 4 ). The coil form has a cylinder wall with holes ( 10 ) or ducts ( 11/1 ) for receiving ends ( 12, 13, 15, 16 ) of the heating wire winding ( 9 ). The connecting conductors ( 18, 19 ) are led radially to the outside through an opening ( 20, 20/1 ) of the outer metal jacket ( 3 ) in an axial area which is located away from the two axial ends of the annular chamber ( 4 ) and is located between two heating wire windings ( 9/1, 9/2 ) or two winding sections ( 9   a,    9   b ) of the same heating wire winding ( 9 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119 ofGerman Patent Application DE 20 2007 010 865.6 filed Aug. 3, 2007, theentire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to an electric cartridge type heater witha continuous central fitting hole for receiving a cylindrical body to beheated, especially a plastic injection molding nozzle, in a gap-freemanner, with an inner metal jacket and an outer metal jacket and with atleast one heating conductor, which is wound as a heating wire winding onthe circumference of a hollow cylindrical coil form, which is insertedin an annular chamber located between the inner and outer metal jackets,is closed on the front side, is surrounded by an insulating compound andconsists of a ceramic mass or a metal oxide and whose cylinder wall hasaxially parallel holes or ducts for receiving the ends of the heatingwire winding and optionally the electric connecting conductors connectedto the ends of the heating wire winding, wherein all parts are compactedby radial pressing.

BACKGROUND OF THE INVENTION

An electric cartridge type heater of the type of this class is known,for example, from DE 103 33 206 A1.

Contrary to other cartridge type heaters, which are used for the samepurpose, for example, for heating a plastic injection molding nozzle,the cartridge type heaters of this class have the advantage that theycan provide a sufficiently long heating wire length for the neededheating capacity with a very small wall thickness of the cylindricalcartridge wall in the compacted state and that they also offer thepossibility of providing a heating capacity distribution over the lengthof the cartridge type heater by selecting different distances betweenwindings in certain axial areas.

While the electric terminals usually exit from the cylindrical cartridgebody on the front side in these prior-art cartridge type heaters, it isrequired in more recent injection molds, especially in molds with aplurality of cavities, that the electric terminals shall not be arrangedon one of the front sides of the cartridge type heater, but somewhere onthe circumference.

Even though there already are heating devices for plastic injectionmolding nozzles with terminals that are arranged radially ortangentially in the middle of the heating body, these heating devicesare wound tubular heating elements, which have a completely differentdesign and are also not comparable to the cartridge type heater of thisclass in terms of capacity.

SUMMARY OF THE INVENTION

The basic object of the present invention is to provide a cartridge typeheater of the type described in the introduction with improvedpossibilities of use, in which especially the electric connectingconductors are not arranged at a front-side end of the cartridge bodybut at a point on the circumference at which they are more readilyaccessible during installation.

This object is accomplished according to the present invention such thatthe connecting conductors connected to the ends of the at least oneheating wire winding and/or the ends of the at least one heating wirewinding are led radially outward through an opening of the outer metaljacket in an axial area located away from the two axial ends of theannular chamber and located between two heating wire windings or twowinding sections of the same heating wire winding.

Due to the cartridge type heater being designed according to the presentinvention, the user has substantially better possibilities concerningthe installation of the cartridge type heater in a predeterminedinjection mold because he is not limited to leading the electricterminals to a front side of the cartridge type heater. The provision ofan opening in the outer metal jacket, through which opening the ends ofthe heating wire winding and/or the connecting conductors thereof can beled to the outside and directed in any desired direction, makes itpossible to design the electric terminals very variably and hence alsoto optimize the possibilities of installation of the cartridge typeheater in an injection mold. In addition, it is, of course, possible toplace the opening of the outer metal jacket such that it is optimallycoordinated for the user or for the particularly intended installationand the possibilities of connection that are provided for in theparticular case.

While it is possible, in principle, to lead to ends of the windings orthe connecting conductors connected to the winding ends to the openingof the outer metal jacket radially outside the heating wire windingpresent, the design offers the considerable advantage that theconnecting conductors connected to the winding ends can be led directlyradially to the outside in the area of the opening of the outer metaljacket from a hole or a duct of the winding support, so that overlapswith the heating wire windings located on the winding support can beavoided.

Different covers may be provided for the opening in the outer metaljacket, and these covers offer a certain protection for the connectingconductors led to the outside, especially if these are not led to theoutside radially but are bent off. In addition, the opening in the outermetal jacket can be tightly closed, so that the cavity that is otherwisepresent can be filled with an insulating compound or a pourable sealingcompound in the area of this opening as well.

The opening in the form of an annular gap has, moreover, the advantagethat the winding support or the winding supports can be pushed in anyrotation position onto the inner metal jacket or into the outer metaljacket, so that the connecting conductors can be led out of the annulargap in any circumferential position.

Various possibilities are available for sealing this gap towards theoutside and for providing possibilities for exiting for the connectingconductors. These possibilities include a ring wall and ring disks.

Since this annular gap forms an empty cavity, in which the winding endsor connecting conductors are arranged, it is possible there, when aplurality of wire windings are provided, to connect these to one anotherin the area of this annular gap or to provide the winding ends of thesewire windings with respective separate connecting conductors and to leadthese radially to the outside through the annular gap.

According to the invention, a winding support may be provided with aplurality of heating wire windings that are each connected to separateconnecting conductors.

The fact that this annular gap is closed towards the outside by means ofa cover is advantageous in the sense that it is possible as a result tofill the cavity present in the area of the annular gap with a pourablesealing compound or an insulating compound and optionally also tocompact it.

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference is made to the accompanying drawings and descriptive matter inwhich the preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a cartridge type heater;

FIG. 2 is a perspective view of the cartridge type heater according toFIG. 1 showing the cover of the opening of the outer metal jacket in aremoved state;

FIG. 3 is a perspective view of the cartridge type heater according toFIG. 1 without the outer metal jacket;

FIG. 3 a is a perspective view of the cartridge type heater according toFIG. 1 without the outer metal jacket but with two separate heating wirewindings on a common winding support;

FIG. 4 is a cross sectional view of the cartridge type heater accordingto FIGS. 1 through 3;

FIG. 5 is a perspective view of a cartridge type heater with acylindrical cover and connecting conductors led radially out of same;

FIG. 5 a is a perspective view of a cartridge type heater with a coverdesigned as a connector plug;

FIG. 6 is a perspective view of the cartridge type heater according toFIG. 5 with the cover removed from the opening;

FIG. 7 is a perspective view of a cartridge type heater with a bent tubeas a cover for a round opening;

FIG. 8 is a perspective view of the cartridge type heater according toFIG. 7 with the cover of the round opening removed;

FIG. 9 is a perspective view of a cartridge type heater with two benttubes as covers for two round openings;

FIG. 10 is a perspective view of the cartridge type heater according toFIG. 9 with the bent tubes as covers for the round openings removed;

FIG. 11 is a perspective view of another cartridge type heater with aring wall as a cover of an annular gap-like opening of the outer metaljacket;

FIG. 12 is a perspective view of a cartridge type heater according toFIG. 11 showing the ring wall in a removed state;

FIG. 13 is a cross sectional view of the cartridge type heater accordingto FIG. 11;

FIG. 14 is an enlarged cross sectional view of another embodiment of thecartridge type heater according to FIG. 11;

FIG. 15 is a cross sectional view taken along line XV-XV of FIG. 14;

FIG. 16 is a perspective view of another embodiment of the cartridgetype heater with a ring wall as a cover, but with the connectingconductors led out axially in parallel;

FIG. 17 is an enlarged cross sectional view of the cartridge type heateraccording to FIG. 16;

FIG. 18 is a perspective view of a cartridge type heater with a ringwall as a cover;

FIG. 19 is an enlarged cross sectional view of the cartridge type heateraccording to FIG. 18;

FIG. 20 is a cross sectional view of another embodiment of the cartridgetype heater;

FIG. 21 is a perspective view of another embodiment of the cartridgetype heater with another cover;

FIG. 22 is a perspective view of the cartridge type heater according toFIG. 21 without cover of the opening of the outer metal jacket, whichthe opening has the shape of an annular gap;

FIG. 23 is a perspective view of a ring wall and an additional cover forthe annular gap according to FIG. 22;

FIG. 24 is a perspective view of another embodiment of the cartridgetype heater with another, cuff-like cover for the opening of the outermetal jacket, which the opening is designed as an annular gap;

FIG. 25 is a perspective view of the cuff-like cover according to FIG.24 as an individual part;

FIG. 26 is a front view taken in the direction of XXVI from FIG. 24;

FIG. 27 is a cross sectional view of the cartridge type heater accordingto FIG. 24;

FIG. 28 is a perspective view of a cartridge type heater with a ringwall and with external threads on a front side;

FIG. 29 is a front view taken in the direction of XXIX from FIG. 28; and

FIG. 30 is a cross sectional view of another embodiment of the cartridgetype heater.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, The cartridge type heater,which will be described below in a plurality of embodiments, is used toheat plastic injection molding nozzles.

It has the following features in all embodiments:

An inner metal jacket 1, which has the shape of a cylindrical tube, isprovided with a central fitting hole 2. This fitting hole 2 is used toreceive a cylindrical body to be heated, namely, a plastic injectionmolding nozzle of an injection mold, in a gap-free manner. An outermetal jacket 3, which is likewise designed as a cylindrical tube andwhich concentrically surrounds the inner metal jacket 1 at a radiallyspaced location and which forms an annular chamber 4 with the innermetal jacket 1, is provided concentrically to the inner metal jacket 1.

This annular chamber 4 is closed at both front-side ends by metallicring disks 5 and 6. A winding support 8 consisting of a ceramic mass ora metal oxide, on the circumference of which at least one heating wirewinding 9 is wound, is seated in the annular chamber 4 on the innermetal jacket. The cylindrical wall of the winding support 8 is providedwith a plurality of axially parallel holes 10 or ducts 11 (FIG. 15),which are provided for receiving the ends 12 and 13 of a heating wirewinding 9 and/or for receiving the connecting conductors 18 and 19connected to the winding ends 12, 13.

The above-mentioned holes 10 and ducts 11 differ only by theircross-sectional shapes. While holes 10 usually have a round crosssection, ducts 11 may have any other desired cross-sectional shape, forexample, a rectangular or oval cross-sectional shape. They have the samefunction within the framework of the present invention.

These holes 10 and ducts 11 may also be used to connect a plurality ofheating wire windings 9, 9/1 or 9/2, which are provided together on awinding support 8 or on a plurality of winding supports 8/1, 8/2, 8/3arranged coaxially with one another on the inner metal jacket 1, forexample, with the use of auxiliary wires 14, or to connect these toseparate connecting wires.

The annular chamber 4 is filled with a compacted insulating compound,for example, MgO (magnesia), in which the heating wire winding isembedded.

As can be best recognized from FIGS. 1, 2 and 4, both the inner metaljacket 1 and the outer metal jacket 3 comprise a one-piece pipe each inthis exemplary embodiment. The outer metal jacket 3 has, approximatelyin its longitudinal center, a rectangular opening 20, through which thetwo connecting conductors 18 and 19 are at first led out radially andare bent off at right angles in the axial direction outside the outermetal jacket 3. A cap-like cover 21 designed as a hollow body isprovided for covering and for closing this opening 20. Two holes 23 areprovided for leading through the two connecting conductors 18 and 19 ina lateral front wall 26 of this cover 21.

The cavity 28 located in the cover 21 is also filled with the insulatingcompound as the annular chamber 4 and optionally compacted.

In the exemplary embodiment according to FIG. 3, the inner metal jacket1 having a one-piece design is provided with a likewise one-piecewinding support 8, which extends over the entire axial length and in theend areas of which two tightly wound winding sections 9 a and 9 b arearranged, while the axial middle area 9 c is provided with a connectionwinding 9 d only. In this one-piece embodiment of the winding support,the latter is provided in the area of the opening 20 with a rectangularrecess 24, which exposes the holes 10 in this area, so that the ends 12and 13 of the heating wire winding, which are led into this recess 24through the holes 10 from the front side, can be bent radially outwardlyand be connected, for example, to the connecting conductors 18 and 19.

One variant of this is shown in FIG. 3 a. Two separate windings 9/1 and9/2, which may be connected to one another in a series connection or ina parallel connection and may be connected to the common connectingconductors 18, 19, are arranged on the common winding support 8according to the embodiment.

In the embodiment according to FIG. 4, which otherwise has the sameoutside appearance, two separate winding supports 8/1 and 8/2 withrespective separate heating wire windings 9/1 and 9/2, which are locatedat an axial distance a from one another in the area of the opening 20but extend into the vicinity of the front-side ring disks 5 and 6, arearranged within the annular chamber 4 on both sides of the opening 20.

In the exemplary embodiment shown in FIG. 4, these two windings 9/1 and9/2 are connected in series by an auxiliary wire 14, which connects twoends 15 and 16 of the winding 9/1, on the one hand, and of the winding9/2, on the other hand, to one another in a contacting manner. Therespective other ends 12 and 13 are connected each by the auxiliarywires 14 to the connecting conductors 18 and 19 in a contacting manner.

As can be recognized from the views in FIGS. 1 through 4, a featureessential for the present invention is that the connecting conductors18, 19, connected to the ends 12 and 13 of the at least one heating wirewinding 9, and/or the ends of the at least one heating wire winding areled radially to the outside through an opening 20 of the outer metaljacket 3 in an axial area 9 c located away from the two axial ends ofthe annular chamber 4 and located between two heating wire windings 9/1,9/2 or two winding sections 9 a and 9 b of the same heating wire winding9.

FIGS. 6 through 10 show a cartridge type heater, whose outer metaljackets 3 have different openings 20/1 compared to the embodimentaccording to FIGS. 1 through 4. These openings 20/1 have a round crosssection and they are also provided with different covers 21/1 and 21/2,respectively. In the embodiment according to FIGS. 5 and 6, the outermetal jacket 3 has a round opening 20/1, which is provided with acylindrical cover 21/1. The upper front surface of this cover 21/1 isclosed by a disk 25, in which two holes 23 are provided for leadingthrough the connecting conductors 18, 19.

The cylindrical cover 21/1 is replaced by a connector plug 21/3 in theembodiment according to FIG. 5 a.

In the embodiment according to FIGS. 7 and 8, which likewise have around opening 20/1, this opening 20/1 is provided with a cover 21/2,which has the shape of a bent tube, through which the connectingconductors 18 and 19 are led to the outside, for example, in a positionin which they are axially parallel, as this is apparent from FIG. 7.

Two round openings 20/1, which are arranged next to each other in thecircumferential direction and which are covered, as in the exemplaryembodiment according to FIGS. 7 and 8, by covers 21/2, which have theform of a bent tube, are provided in the embodiment according to FIGS. 9and 10. Two connecting conductor pairs 18 and 19 are provided in thiscase, which are led to the outside through the openings 20/1 and thecovers 21/2 in the manner shown in FIG. 9 in a position in which theiraxes are located in parallel.

The inner structure of these cartridge type heaters according to FIGS. 5through 10 can correspond, for example, to that according to FIG. 4. Inthe embodiment according to FIGS. 9 and 10, it is possible to providethe two heating wire windings 9/1 and 9/2 according to FIG. 4 withseparate connecting conductor pairs 18 and 19 each, so that these can beactivated independently from each other.

The outer metal jacket 3 has a two-part design in the exemplaryembodiments described below, so that it comprises two sections 3/1 and3/2, which have the same diameter and which form between them an annulargap as an opening 20/2, through which the connecting conductors 18 and19 can be led radially to the outside.

In the exemplary embodiments 11 through 15, the inner metal jackets 1also comprises two parts 1/1 and 1/2 each, which join each other on thefront side in the middle in the opening 20/2 designed as an annular gapand can also be connected to one another there by welding. It is thuspossible to manufacture a left half and a right half of the entirecartridge type heater individually with a wire-wound winding support 12and 13, respectively, and to fit these together coaxially in theprefabricated state. The two annular chambers 4, which are connected toone another, may be filled with the granular insulating material, e.g.,MgO, and compacted, in the already fitted state, and it is possibleafter the compacting to expose the ends of the heating wire windings 9/1and 9/2, which ends are led into the opening 20/2, or to expose theheating wires 14 connected to these and, e.g., to connect these to theconnecting conductors 18 and 19.

A ring wall 30, which has a larger diameter than the two outer metaljacket sections 3/1 and 3/2, which have equal diameters, is provided asa cover for the opening 20/2 comprising the annular gap, so that thereis a radial distance R circumferentially between these. Ring disks 31and 32, which are tightly connected, e.g., welded, to the ring wall 30and to the two opposite ends of the outer metal jacket sections 3/1 and3/2, are provided in the area of this radial distance R. Like theannular chamber 4, the cavity 34 formed when arranging the ring wall 30and the two ring disks 31 and 32 is subsequently filled with a granularinsulating material, e.g., MgO or with a pourable sealing compound,e.g., epoxy resin, silicone rubber, ceramic putty compound or the likeand optionally compacted.

To make it possible to lead the connecting conductors 18 and 19connected to the auxiliary wires 14 or to the ends 12 and 13 out of theopening 20/2, the ring wall 30 is provided with two radial passageopenings 23.

As can be recognized from FIG. 12, it is also possible, for example, themake the ring disk 31 integrally in one piece with the ring wall 30 ifthis is manufactured, for example, as a deep-drawn part and to arrangethe second ring disk later in order to closingly bridge over the radialdistance R on its side.

As is apparent from FIGS. 13 and 14, there are, in principle, twopossibilities of connecting the two windings 9/1 and 9/2 of the twoseparate winding supports 8/1 and 8/2, They may be connected inparallel, as this is provided in the exemplary embodiment according toFIG. 13, or in series, as this is shown in the exemplary embodimentaccording to FIG. 14. FIG. 14 also shows how the cavity 34 that isinitially present in the area of the opening 20/2 designed as an annulargap is filled with the same granular insulating material as the annularchambers 4, which will then be contiguous and are formed by the twosections 1/1 and 1/2 of the inner metal jacket 1 and by the two sections3/1 and 3/2 of the outer metal jacket 3. These annular chambers 4 areclosed by the ring disks 5 and 6 on the front side in all embodiments.

FIGS. 16 through 30 show different exemplary embodiments, which have asan opening 20/2 in the outer metal jacket, an annular gap each, whoseinner metal jacket 1 is, however, of a one-piece design and extends overthe entire length of the cartridge type heater.

As in the exemplary embodiment according to FIG. 3, a winding support 8,which extends essentially over the entire length of the two joinedannular chambers 4 and on which a contiguous heating wire winding 9 isarranged, is also provided in the exemplary embodiment according toFIGS. 16 and 17, but the heating wire winding 9 has two tightly woundsections 9 a and 9 b, between which the opening 20/1 designed as anannular gap is arranged. These two winding sections 9 a and 9 b areconnected to one another by one or more winding turns 9 d of a greaterpitch. The winding ends 12 and 13 introduced into a hole 10 of thewinding support 8 from the front side are connected to the twoconnecting conductors 18 and 19 by auxiliary wires 14 in an electricallyconductive manner. These two connecting conductors 18 and 19 are led tothe outside in this exemplary embodiment as well as in other exemplaryembodiments through a ring disk 32 rather than radially through the ringwall 30, as this appears, for example, from FIG. 17.

It is shown in this example that the opening 20/1, through which theconnecting conductors 18 and 19 are led to the outside, is arrangedbetween two winding sections 9 a and 9 b at a point that is arrangedaway from the front-side ends of the annular chamber 4 and from the ringdisks 5 and 6, which limit the annular chamber 4 on the front side.

This axial distance of the opening 20, 20/1, 20/2 from the two ends ofthe cartridge type heater, i.e., from the ring disks 5 and 6, may beequal or different.

The exemplary embodiment according to FIGS. 18 and 19 has essentiallythe same inner structure as the exemplary embodiment according to FIG.13. However, a thermocouple 42, which comprises two thermoelectric wires40 and 41 consisting of different metals and whose terminals 44 are ledto the outside through corresponding openings of the ring disk 31, isarranged in a hole 10 of one winding support 8/1. The ring disks 32 arecompletely closed in this case. The ring wall 30 is provided as a coverfor the opening 20/2 designed as an annular gap in this case as well.The structure is otherwise the same as in the exemplary embodimentaccording to FIG. 13.

FIG. 18, which is a perspective view of the exemplary embodimentaccording to FIG. 19, shows how the connecting conductors 18 and 19 aswell as the terminals of the thermocouple 42 are led to the outside.

Three winding supports 8/1, 8/2 and 8/3, which are provided withseparate heating wire windings 9/1, 9/2 and 9/3 each, are arranged on aone-piece inner metal jacket 1 in the exemplary embodiment according toFIG. 20, which is shown in a sectional view. The opening 20/1, which isdesigned as an annular gap in this embodiment as well, is locatedbetween the two winding supports 8/2 and 8/3 and thus also between thetwo windings 9/2 and 9/3. This opening 20/1 is closed by the ring wall30 and the two ring disks 31 and 32 in this case as well. The ring wall30 has two radial holes 23, through which the two connecting conductors18 and 19 are led radially to the outside. While the ends 13 of allthree heating wire windings 9/1, 9/2 and 9/3, which ends are located inthe lower hole 10, are connected to one another by an auxiliary wire 14and these windings are thus connected in parallel, the two ends 12 ofthe windings 9/1 and 9/3, which ends are located in the upper hole 10,are connected by an auxiliary wire 14 together with the connectingconductor 18.

The other auxiliary wire 14 is led into an upper hole 10 of the windingsupport 8/2, where it contacts the upper winding end 12 of the heatingwire winding 9/2 and connects same to the connecting conductor 19.

FIGS. 21 through 23 show an embodiment in which the opening 20/2designed as an annular gap is closed for the most part by a ring 36bridging over the annular gap between the two outer metal jacketsections 3/1 and 3/2. This ring 36 has an interruption 37, into which acover 21 is fittingly inserted. As in FIG. 1, two connecting conductors18 and 19 are led through this cover 21 to the outside in an axiallyparallel manner through holes 23 in a front wall 26.

In the exemplary embodiment shown in FIGS. 24 through 27, whose innerstructure corresponds to that of FIG. 17, the opening 20/1 designed asan annular gap is closed with a ring wall, which is directly andconnectingly in contact with the two outer metal jacket sections 3/1 and3/2. This ring wall 33 is provided with a hood-like expansion 21/2,which projects radially to the outside and whose function corresponds tothat of the cover 21. This hood-like expansion 21/2 is closed on thefront side by wall elements 38 and 39. The wall element 38 has two holes23, through which the connecting conductors 18 and 19 can be led to theoutside. The cavity 34 in the area of the annular gap-like opening 20/1and of the expansion 21/2 is filled with granular MgO or with a pourablesealing compound and optionally compacted in this embodiment as well.

The inner structure of this embodiment, shown as a sectional view inFIG. 27, otherwise corresponds to that in FIG. 17.

FIGS. 28 and 29 show an exemplary embodiment in which a metal ring 45with an external thread 46 is arranged concentrically at one end of thecartridge type heater. It is possible by means of this external thread46 to fasten the cartridge type heater on a cylindrical injectionmolding nozzle, for example, by means of a so-called union nut, in asimple manner.

The winding ends of the heating wire winding or heating wire windings,which heating wire windings are arranged in the interior of thecartridge type heater, are connected to the connecting conductors 18 and18 in the above-described manner via auxiliary wires and by means of amineral-insulated two-wire line 48 in this cartridge type heater, whichis likewise provided with a ring wall 30 and with a ring disk 31.

Mineral-insulated lines comprise, as a rule, a metal jacket, in whichelectric conductor wires are embedded in a highly compacted granularmineral insulating material, These mineral-insulated lines, which may beof a single-wire or multiwire design, have a high temperature stability.They are therefore especially suitable and can be especially recommendedfor cartridge type heaters of the type being described here, becausetemperatures that are not withstood by the plastic insulations of usualelectric lines may occur in them and in the environment in which theyare installed. It is therefore useful to generally use suchmineral-insulated lines as connecting conductors 18 and 19 in cartridgetype heaters of the type of this class.

Finally, FIG. 30 also shows a sectional view of an embodiment with anannular gap-like opening 20/1, which is closed with a ring wall 33,which has the radial expansion 21/2. The two winding supports 8/1 and8/2, which are arranged on both sides of the opening 20/1, are separatedfrom each other by a spacer ring 47 in this embodiment. This spacer ring47 has an external diameter that is selected to be such that the holes10 of the two winding supports 8/1 and 8/2, respectively, lie freely onthe side facing the opening 20/1 and are thus freely accessible for theinsertion of winding ends or conductor wires 14. The windings 9/1 and9/2 of the two winding supports 8/1 and 8/2 are connected in series bymeans of an auxiliary wire 14, which connects the two winding ends 15and 16 to one another, in this embodiment as well.

The respective other winding ends 12 and 13 are connected by auxiliarywires 14 to the conductors 54 and 55 of two mineral-insulated lines 56and 57, to which the connecting conductors 18 and 19 are connected.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

1. An electric cartridge type heater, comprising: an inner metal jacketdefining a continuous central fitting hole for receiving a cylindricalbody in a gap-free manner; an outer metal jacket surrounding said innermetal jacket, said inner metal jacket and said outer metal jacketdefining an annular chamber such that said annular chamber is locatedbetween said inner metal jacket and said outer metal jacket, saidannular chamber being closed on a front side; a hollow cylindrical coilform having a cylinder wall with a circumferential surface, saidcylinder wall defining a plurality of axially parallel holes; a heatingconductor in the form of a first heating wire winding and a secondheating wire winding, said first heating wire winding and said secondheating wire winding being wound about said circumferential surface ofsaid hollow cylindrical coil form, said hollow cylindrical coil formwith said first heating wire winding and said second heating wirewinding being located within said annular chamber, each hole of saidcylinder wall receiving one end of said first heating wire winding orone end of said second heating wire winding; electric connectingconductors, each electric connecting conductor receiving another end ofsaid first heating wire winding or another end of said second heatingwire winding, said outer metal jacket having an outer metal jacketsurface defining a wire opening located at a spaced location from eachaxial end of said annular chamber and between said first heating wirewinding and said second heating wire winding, said electric connectingconductors radially extending through said wire opening to a positionlocated outside of said outer metal jacket; and an insulating compoundconsisting essentially of a ceramic mass or a metal oxide, saidinsulating compound filling said annular chamber and surrounding saidhollow cylindrical coil form such that said hollow cylindrical coilform, said first heating wire winding, said second heating wire windingand said inner metal jacket are radially compacted via said insulatingcompound.
 2. An electric cartridge type heater in accordance with claim1, wherein at least one of said holes of said hollow coil form is incommunication with said wire opening in an axial area of said wireopening, one said winding end of said first heat wire winding or saidsecond heat wire winding and/or one of said connecting conductorsextending through said at least one hole to said wire opening.
 3. Anelectric cartridge type heater in accordance with claim 1, wherein saidwire opening has a cover arranged on said outer metal jacket surface forreceiving said connecting conductors extending from said wire opening.4. An electric cartridge type heater in accordance with claim 3, whereinsaid wire opening is limited axially and in the circumferentialdirection.
 5. An electric cartridge type heater in accordance with claim4, wherein said cover is a connector plug having at least two contactpins, one contact pin being connected to one end of said first heatingwire winding, another contact pin being connected to one end of saidsecond heating wire winding.
 6. An electric cartridge type heater inaccordance with claim 4, wherein said cover comprises a hollow bodysurrounding said wire opening, said hollow body defining at least onepassage opening for receiving one of said connecting conductors, saidpassage opening extending at least approximately axially in parallel toa longitudinal axis of said hollow cylindrical coil form.
 7. An electriccartridge type heater in accordance with claim 4, wherein said covercomprises a bent tube with a radial tube section and an axially paralleltube section.
 8. An electric cartridge type heater in accordance withclaim 3, wherein said cover comprises an essentially radially extendingtube section.
 9. An electric cartridge type heater in accordance withclaim 1, wherein said outer metal jacket comprises a first jacketsection having a first jacket section front side and a second jacketsection having a second jacket section front side, said first jacketsection being coaxial with said second jacket section, said first jacketsection being disposed at a spaced location from said second jacketsection such that said first jacket section front side and said secondjacket section front side define an annular gap, said annular gap beingradially surrounded by a ring wall, said ring wall defining at least oneradial passage opening for receiving one of said connecting conductors.10. An electric cartridge type heater in accordance with claim 9,further comprising a first circumferential ring disk and a secondcircumferential ring disk, wherein said ring wall is located at a spacedlocation from said first jacket section and said second jacket section,said first circumferential ring disk being located on one side of saidring wall and said circumferential ring disk being located on anotherside of said ring wall such that said first circumferential ring diskand said second circumferential ring disk close the space between saidring wall and said first jacket section and said second jacket section.11. An electric cartridge type heater in accordance with claim 10,wherein at least one of said circumferential ring disk defines at leastone conductor passage opening for receiving one of said connectingconductors.
 12. An electric cartridge type heater in accordance withclaim 10, wherein said heating conductor includes a third heating wirewinding, each end of said first heating wire winding, said secondheating wire winding and said third heating wire winding being connectedin a cavity enclosed by said ring wall.
 13. An electric cartridge typeheater in accordance with claim 12, further comprising a pourablesealing compound including one or more of epoxy resin, silicone rubberand ceramic putty compound, wherein said cavity enclosed by said ringwall is filled with said pourable sealing compound.
 14. An electriccartridge type heater in accordance with claim 13, wherein said cavityenclosed by said ring wall is filled with the same insulating compoundas said annular chamber containing said heating wire windings.
 15. Anelectric cartridge type heater in accordance with claim 1, furthercomprising a first metallic disk connected to one side of said innermetal jacket and said outer metal jacket and a second metallic diskconnected to another side of said inner metal jacket and said outermetal jacket, said first metallic disk and said second metallic diskenclosing said annular chamber.
 16. An electric cartridge type heater inaccordance with claim 1, wherein said first heating wire winding isconnected to one connecting conductor and said second heating wirewinding is connected to another connecting conductor.
 17. An electriccartridge type heater in accordance with claim 1, wherein said firstheating wire winding is wound about a first circumferential portion ofsaid hollow cylindrical coil form, said second heating wire windingbeing wound about a second circumferential portion of said hollowcylindrical coil form, said first portion of said hollow cylindricalcoil form with said first heating wire winding being coaxial with saidsecond portion of said hollow cylindrical coil form with said secondheating wire winding, said first portion of said hollow cylindrical coilform being disposed at a spaced location from said second portion ofsaid hollow cylindrical coil form such that said first portion of saidhollow cylindrical coil form is opposite said second portion of saidhollow cylindrical coil form in an axial area of said wire opening, saidinner metal jacket extending the entire length of the cartridge typeheater, said heating wire windings being connected in series or inparallel, one end of said first heating wire winding being connected toone end of said second heating wire winding, said end of said firstheating wire winding and said end of said second hearing wire windinghaving a common connecting conductor.
 18. An electric cartridge typeheater in accordance with claim 1, further comprising an auxiliary wireextending through one of said holes of said hollow cylindrical coil formand connected to one of said connecting conductors, wherein one end ofsaid first heating wire winding and one end of said second heating wirewinding are connected to said auxiliary wire, said first heating wirewinding and said second hearing wire winding comprising a round wire.19. An electric cartridge type heater in accordance with claim 18,wherein each connecting conductor comprises mineral-insulated lineshaving conductor wires directly connected to one end of said firstheating wire winding or one end of said second heating wire winding orconnected to said first heating wire winding or said second heating wirewinding via said auxiliary wire.
 20. An electric cartridge type heaterin accordance with claim 1, wherein said first heating wire winding andsaid second heating wire winding are wound about said hollow cylindricalcoil form such that each winding of wire is at a distance that isdifferent than another winding of wire over the length of said hollowcylindrical coil form.
 21. An electric cartridge type heater inaccordance claim 1, further comprising a metal ring having an externalthread fastened to a front-side free end of said outer metal jacket. 22.An electric cartridge type heater in accordance with claim 1, furthercomprising a spacer ring arranged between a first portion of said hollowcylindrical coil form and a second portion of said hollow cylindricalcoil form in an area of said wire opening of said outer metal jacket,said first portion of said hollow cylindrical coil form being arrangedcoaxial with said second portion of said hollow cylindrical coil formwithin said annular chamber, said first portion of said hollowcylindrical coil form and said second portion of said hollow cylindricalcoil form having axial holes, said spacer ring maintaining said firstportion of said hollow cylindrical coil form at a spaced location fromsaid second portion of said hollow cylindrical coil form such that saidaxial holes of said first portion and said second portion are exposed.23. An electric cartridge type heater in accordance with claim 1,further comprising thermoelectric wires arranged in at least one hole ofsaid hollow cylindrical coil form, each end of one thermoelectric wirebeing connected to another end of another thermoelectric wire to form athermocouple.
 24. An electric cartridge type heater, comprising: aninner metal sleeve defining a continuous central fitting space forreceiving a plastic injection molding nozzle in a gap-free manner; anouter metal sleeve surrounding said inner metal sleeve; a first metallicdisk engaging said inner metal sleeve and said outer metal sleeve at afront side thereof; a second metallic disk engaging said inner metalsleeve and said outer metal sleeve at a rear side thereof, said firstmetallic disk, said second metallic disk, said inner metal sleeve andsaid outer metal sleeve defining an annular chamber; a cylindricalwinding support in contact with said inner metal sleeve, saidcylindrical winding support having a first cylinder wall with a firstcircumferential surface and a second cylinder wall with a secondcircumferential surface, said first cylinder wall defining a pluralityof first axially parallel holes, said second cylinder wall defining aplurality of second axially parallel holes; a first heating wire windingwound about said first circumferential surface of said cylindricalwinding support; a second heating wire winding wound about said secondcircumferential surface of said cylindrical winding support, said firstheating wire winding and said second heating wire winding defining aheat conductor, said cylindrical winding support with said first heatingwire winding and said second heating wire winding connected theretobeing located within said annular chamber, each first hole of said firstcylinder wall receiving one end of said first heating wire winding, eachsecond hole of said second cylinder wall receiving one end of saidsecond heating wire winding; a first electric connecting conductorreceiving another end of said first heating wire winding; a secondelectric connecting conductor receiving another end of said secondheating wire winding, said outer metal jacket having an outer metaljacket surface defining a conductor opening located at a spaced locationfrom said first metallic disk and said second metallic disk, saidconductor opening corresponding to an area of said cylindrical windingsupport that is located between said first heating wire winding and saidsecond heating wire winding, said first electric connecting conductorand said second electric connecting conductor extending radially from aposition within said annular chamber to a position located outside saidouter metal sleeve via said conductor opening; an insulating compoundcomprising at least one of a ceramic mass and metal oxide, saidinsulating compound being located within said annular chamber such thatsaid insulating compound surrounds said cylindrical winding support toradially compress said cylindrical support, said first heating wirewinding, said second heating wire winding and said inner metal jacket.25. An electric cartridge type heater according to claim 24, whereinsaid first heating wire winding is connected to said second heating wirewinding.